Question

In the transverse section of myofibril, the region of A band where thick and thin filaments overlap, each actin filament is surrounded by __(A)__thick filaments and each myosin filament is surrounded by __(B)__ thin filaments.

• A. (A) 3 (B) 3
• B. (A) 6 (B) 3
• C. (A) 6 (B) 3
• D. A) 3 (B) 6

Answer 1

The correct option is D A) 3 (B) 6

A myofibril (also known as a muscle fibril or sarcostyle) is a basic rod-like organelle of a muscle cell. The myofibrils are made up of thick and thin myofilaments. The thick filaments are composed of myosin, and the thin filaments are predominantly actin, along with two regulatory proteins, tropomyosin and troponin.

Structural arrangement of actin and myosin in A band is such that each actin filament is surrounded by 3 thick (myosin) filaments and each myosin filament is surrounded by 6 thin (actin) filaments.